Aircraft seats that are occupied during certain phases of aircraft operation, e.g., taxi, take-off, climb, descent, and/or turbulence encounters, must be provided with an occupant restraint system. Aircraft occupant seat restraint systems will typically include a lap belt assembly comprised of a pair of opposing lap belt sections, one having a female buckle provided on its terminal end and the other having a belt length-adjustable male tab assembly at its terminal end which is capable of being cooperatively received in and released from the female buckle. Such conventional aircraft occupant seat restraint systems are satisfactory for forward or rearward facing aircraft seats that are oriented generally in alignment with the aircraft's flight direction (e.g., parallel to the aircraft's longitudinal axis) since the conventional lap belt assembly restrains the occupant symmetrically relative to the centerline of the aircraft seat (i.e., the midsagittal plane of an occupant's body is symmetrically aligned with the positional centerline of the seat). Such symmetrical midsagittal positioning of the occupant on the aircraft seat thereby ensures that the lap belt assembly will provide maximum occupant restraint due to the longitudinal forces aligned with the direction of aircraft movement that are typically encountered.
Side-facing aircraft seats, i.e., seats where the seat causes the midsagittal plane of the occupant to be substantially perpendicular to the aircraft's longitudinal axis, present certain problems with respect to occupant safety. For example, conventional lap belt systems are typically less effective when the occupant is side-facing rather than forward or rearward facing. One example of a side-facing aircraft seat that may be occupied during all phases of aircraft operation is a convertible belted toilet seat, i.e., an aircraft monument whereby a passenger seat is provided as a removable cover for an on-board toilet. Convertible belted toilet seats may thus be employed in some aircraft interior configurations, especially business-class aircraft, so as to increase the maximum aircraft occupancy (i.e., since the belted toilet seat can accommodate an additional occupant during all phases of aircraft operation) while still providing an on-board toilet facility for all occupants.
One prior proposal to provide occupant restraint systems for side-facing aircraft seats is apparent in U.S. Pat. No. 8,939,465, the entire content of which is expressly incorporated hereinto by reference. According to the proposal in such patent, the occupant's midsaggital plane is aligned substantially coincident with the seat's positional centerline. The side-facing seat has a conventional lap belt restraint system that may be supplemented with a shoulder belt. Additional supplemental occupant restraint is also provided according to such prior proposal by means of an inflatable airbag assembly on the side of the occupant toward the front of the aircraft.